PSI - Issue 22

Maria da Luz Garcia et al. / Procedia Structural Integrity 22 (2019) 166–170 Maria da Luz Garcia, Rosário Oliveira/ Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction The walls of the old buildings have, in their great majority, a high thickness in order to support structural loads and to exert thermal protection, being verified that they have some permeability to the water, through infiltrations by several points in that the borders or the interfaces allow, although the construction system was favorable to the rapid drying of this water. Therefore, the coating of these walls besides being compatible with the support must have a good capacity of mechanical resistance and high durability Santos and Veiga (2012). Application of the hydraulic lime mortar base in the rehabilitation of old buildings, have shown a good workability; good adhesion to surfaces; reduction of cracking (due to its adhesiveness, and low retraction); good mechanical strength; increased profitability of hand-work and good finishing, thereby helping to increase the quality of old buildings. In Portugal increasingly uses pre-dosed commercial mortar in place of traditional mortar for plaster of building walls, due to the urgent need for intervention in the old building, mainly as regards the structural and aesthetic part, as well as economic advantage, in the However, there are disadvantages such as the lack of complete knowledge of its composition, and it cannot correctly evaluate the performance of these mortars, Faria et al. (2011), as well as the knowledge of the compatibility of the mortars with the support that receives it. This article evaluates the difference between a traditional mortar of hydraulic lime and commercial mortar (hydrated lime, pozzolanic and hydraulic binders) used in the rehabilitation of walls of old buildings, in terms of mechanical behavior and behavior, as well as the absorption of water by capillarity and by immersion. 2. Experimental Program The experimental program consisted in the comparative analysis between two lime mortars with the regulatory recommendations in terms of mechanical resistance and water absorption. For this purpose, a hydraulic lime mortar was produced according to the procedures of norm NP EN 196 -1 and a prefabricated mortar according to the procedures of respective commercial technical form. The tests were carried out at the Construction Materials Laboratory of the Department of Civil Engineering of the Superior Engineering Institute of Porto, expecting the pullout test that was carried out at the place where the mortars analyzed were to be applied. 2.1. Production of mortars A HL5 hydraulic lime mortar with a sand of medium particle size at a 1: 3 trace and a water / cement ratio of 0.5 was prepared according to the procedures of standard NP EN 196-1. The second prefabricated mortar, for each 25 kg bag, is mixed with 4 liters of water, with a mechanical mixer at a constant speed of rotation according to the procedures of the commercial entity's data sheet. 2.2. Mechanical strength The flexural and compressive strengths were determined at 28, 56 and 70 days according to the procedures described in standards EN 1015-11 and NP EN 196-1, in prismatic 40 × 40 × 160 mm specimens.